This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. The specific aims of this study are: 1) to evalute the effect of once a week Epo dosing on reticulocytes and hematocrits and 2) compare reticulocyte responses of once a week dosing with thrice weekly dosing of Epo in preterm infants. We will also test the following hypothesis: 1) Epo administered three times a week to preterm infants will increase reticulocytes to a greater degree than Epo administered once a week.